Chapter 45- Sensory Systems Flashcards Preview

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Flashcards in Chapter 45- Sensory Systems Deck (46):
1

Sensory Receptors overview

provide information from internal and external environments

2

exteroceptors

sense external stimuli

3

interoceptors

sense internal stimuli

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3 classes of Receptors

1. mechanoreceptors
2. chemoreceptors
3. electromagnetic receptors

5

Mechanoreceptors

stimulated by mechanical forces such as pressure
-receptors in skin
-respond to stimuli at border btwn internal and external envir.

6

Chemoreceptors

detect chemicals or chemical changes
-ex. smell, taste

7

Electromagnetic receptors

react to heat and light energy
-ie. vision, heat

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4 step process of CNS perceivance

1. Stimulation-of sensory receptor cells
2. transduction-in sensory receptor cells
3. Transmission-along one or more sensory neurons
4. interpretation-in CNS

9

Receptor potential

-sensory cells respond to stimuli via stimulus-gated ion channels in membrane
-if stimulus is of sufficient magnitude, a depolarization of the receptor cell occurs

10

Nociceptors

-mechanoreceptor
-transmit impulses perceived as pain
-most consist of free nerve endings located throughout body, especially surface

11

Thermoreceptors

-mechanoreceptor
-naked dendritic endings of sensory neurons that are sensitive to changes in temp.
-cold receptors located higher in skin

12

2 types of mechanoreceptors that respond to touch

-phasic-intermittently activated, hair follicles
-tonic-continuously activated

13

Proprioreceptors

-monitor muscle length and tension
-provide info about relative position or movement of animals body parts

14

Baroreceptors

-monitor blood pressure
-located at carotid sinus and aortic arch
-detect tension or stretch in the walls of these blood vessels
-when blood pressure decreases the frequency of barometric impulses decreases

15

Hearing (what is it)

-detection of soundwaves
-sound is the result of vibration traveling through a medium
-detection is possible through action of specialized mechanoreceptors in inner ear

16

lateral line system in fish

-consists of hair cells within longitudinal canal in the fishs skin
-hair cells are innervated by sensory neurons that transmit impulses to brain

17

How does vertebrate hearing occur

-tympanic membrane vibrates causing movement in malleus, incus, and stapes
-stapes vibrates against oval window
-pressure waves vibrate through cochlea
-depolarizes hair cells which send action potentials to brain

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Echolocation

-mammals that can perceive presence and distance of objects by sound
-bats, shrews, whales, dolphins

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Statocyst

invertebrates use this to orient themselves with respect to gravity

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Utricle and Saccule

gravity receptors in vertebrates consisting of two chambers (as mentioned) in the membranous labyrinth
-utricle is more sensitive to horizontal acceleration
-saccule is more sensitive to vertical acceleration

21

Vestibular Apparatus

-saccule, utricle and semicircular canals
-together they detect gravity changes

22

Chemoreceptors

-bind to particular chemicals in the extracellular fluid
-membrane of sensory neuron becomes depolarized and produces action potentials
-used in the senses of taste and smell
-important in monitoring chemical composition of blood

23

Gustation

-Taste
-mixture of physical and psychological factors
-taste buds are collections of chemosensitive cells associated with afferent neurons

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5 categories of taste

-sweet
-sour
-salty
-bitter
-umami (hearty)

25

Olfaction

-involves neurons located in upper portion of nasal passages
-receptors project into nasal mucosa, and their axons project directly into the cerebral cortex
-particles must first dissolve into extracellular fluid before they can activate the olfactory receptors

26

Vision

-begins with capture of light by photoreceptors
-used to determine both direction and distance of object

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Flatworm eyes

-can perceive direction of light but no visual image

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what 4 phyla have well developed image forming eyes

-annelids
-mollusks
-arthropods
-chordates

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Sclera

white portion of the eye, formed of tough connective tissue

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Cornea

-transparent portion through which light enters, begins to focus light

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Iris

colored portion of the eye
-contraction of the iris muscles in bright light decreases the size of its opening, the pupil

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Lens

transparent structure that completes focusing of light onto the retina

33

Near vs. Far vision

-lens is attached to ciliary muscles, changes shape of lens
-near vision=ciliary muscles contract-more bending of light
-far vision=ciliary muscles relax-less light bending

34

Rods

-on retina
-responsible for black and white vision when illumination is dim

35

Cones

-on retina
-responsible for color vision and high visual acuity
-momst are located in central region of retina known as focea

36

Basic structure of rods and cones

-inner segment rich in mitochondria and vesicles filled with neurotransmitter molecules
-packed with hundreds of flattened disks which contain photopigments

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Photopigment in rods

rhodopsin

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Photopigment in cones

photopsins
-3 kinds of cones

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3 layers of retina

1. external layer contains rods and cones
2. middle layer contain bipolar cells
3. layer closest to eye cavity contains ganglion cells
--photoreceptors activate bipolar cells which activate ganglion cells which transmit impulses to brain via optic nerve

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What happens to eyes in the dark

-photoreceptor cells release an inhibitory neurotransmitter that hyperpolarizes the bipolar neurons
-prevents the bipolar neurons from releasing excitatory neurotransmitter to the ganglion cells that signal to the brain

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What happens to eyes in the light

-photoreceptor cells stop releasing their inhibitory neurotransmitter, in efect, stimulating bipolar cells
-bipolar cells in turn stimulate the ganglion cells, which transmit action potentials to the brain

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Visual Processing

-action potentials in the optic nerves are relayed from the retina to the lateral geniculate nuclei of the thalamus
-then projected to the occipital lobes of cerebral cortex

43

Color blindness

-lack of one or more types of cones
-sex linked recessive trait
-people with normal vision are trichomats

44

Binocular vision

-primates and most predators have 3 eyes on each side of face
-2 fields of vision overlap (binocular vision)
-prey have eyes on both sides of head

45

Detection of electrical currents

-elasmobranches (sharks, rays, skates) have electroreceptors called ampullae of lorenzini that sense electrical currents generated by muscle contractions of prey

46

Detection of Magnetic fields

-eels, sharks, bees and many birds appear to navigate along the magnetic field lines of earth